Abstract:
The Open Geospace General Circulation Model (Open GGCM) was originally developed as a magnetohydrodynamic (MHD) model of Earth's magnetosphere at UCLA in the early 1990's by J. Raeder. Besides solving the resistive MHD equations in the magnetosphere the model included a rather crude ionospheric boundary condition consisting of a ionosphere potential solver that served to close the magnetospheric ... field-aligned currents in the ionosphere and thus coupled magnetospheric convection with ionospheric convection. Subsequently the ionosphere end of the model was improved by adding a magnetosphere-ionosphere coupling module that not only mapped the field-aligned currents into the ionosphere and the potential back into the magnetosphere, but also computed electron precipitation parameters and the ionospheric Hall and Pedersen conductances using empirical relations in a self-consistent manner. In the late 90's this model was coupled with CTIM (Coupled Thermosphere Ionosphere Model, developed by T. Fuller-Rowell, NOAA/SEC), a sophisticated three-dimensional dynamical models of the thermosphere and ionosphere. CTIM takes the potential and the electron precipitation parameters from the MHD model and provides in turn the conductances and the ionospheric dynamo current to the potential solver. CTIM thus replaces the empirical conductance calculations with first-principle calculations. However, it also adds substantial physics to the model, and its outputs are highly relevant space weather parameters, such as the ionospheric electron parameters (Nmf2, hmf2) and neutral densities and composition. The coupled model was known for some time as the UCLA/NOAA GGCM and is now Open GGCM.

Raeder, J., and V. Angelopoulos, Using global simulations of the magnetosphere for multi-satellite mission planning and analysis, in: Science Closure and Enabling Technologies for Constellation Class Missions, UCB and NASA GSFC pub 78, 1998. (An example of how to use the global model to help define missions)